Relationships between major milk whey proteins in blood plasma and
milk yield in dairy cattle.
C.A. Morris, S.R. Davis, S.J. Eichler, N.G. Cullen.
AgResearch, Ruakura Agricultural Research Centre, Private Bag 3123,
Hamilton, New Zealand.
Proceedings of the New Zealand Society of Animal Production 1994,
54: 121-124
The objective of this study was to investigate phenotypic variation in
alpha-lactalbumin (alpha-lac) and Beta-lactoglobulin (Beta-lg) concentrations
in the blood plasma of cows immediately before calving, and to evaluate their
use as predictors of the subsequent lactation yields of milk or milk solids.
Fifty-nine Jerseys (all ages) at Ruakura No. 2 and 148 Jerseys (all 2-year-olds)
in a private Waikato herd were blood sampled in July immediately before calving.
Data for plasma loge ý-lac and loge ·-lg concentrations were adjusted for date
of calving and (in the Ruakura herd) for stocking rate and age of cow, and
regressions and correlations were estimated with subsequent lactation yields of
milk, milkfat, protein and lactose (also adjusted for known fixed effects
including lactation length). Correlations of adjusted loge ý-lac with adjusted
yields in the Ruakura herd were 0.33 (P<0.05) for milk, 0.29 (P<0.05) for
milkfat, 0.25 for protein and 0.32 (P<0.05) for lactose. The residual standard
deviation for milkfat was reduced from 16.5 to 16.0 kg. Correlations were
smaller and not significant in the private herd. After adjusting yields
additionally in the Ruakura herd for live weight, correlations of adjusted
loge ý-lac with adjusted yields ranged from 0.35 to 0.40 (mostly P<0.01),
and residual standard deviations of yield were further reduced (e.g. from
15.3 to 14.3 kg for milkfat). Correlations between adjusted loge ·-lg and
adjusted yield were small and not significant in either herd. Adjusted loge
alpha-lac and adjusted loge Beta-lg had a correlation of 0.56 in herd 1 and 0.14
in herd 2. The use of loge Beta-lac to predict adjusted yield in the subsequent
lactation deserves further assessment.
Keywords: NZSAPAB;
cattle; milksolids yield; alpha-lactalbumin; Beta-lactoglobulin.
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Last Updated 25-01-1997
